ATLANTA – Whenever Yu Darvish takes the mound, what’s going on between his ears seems just as important as what’s coming out of his right arm.

One obviously affects the other. But it’s nearly impossible to really know whether a balk, a bad walk or a leg cramp has led Darvish to lose focus and unravel in previous starts, including his most recent one, a slightly abbreviated four-inning outing in Atlanta on Tuesday.

Darvish’s early returns have been mixed, to say the least, with a 5.56 ERA and 1.53 WHIP. He’s only gotten out of the fifth inning twice in seven starts. Why has he underperformed early? We know he hasn’t been using his deep arsenal exactly as had been hoped.

During the spring, there was a lot of discussion of Darvish using his changeup and curveball more often. But according to Pitch Info, through seven starts Darvish’s curveball usage is down to a career-low 3.4 percent; the changeup is being flashed occasionally at...